Temperature-compensated current monitoring

ABSTRACT

Systems, methods and media for current monitoring are provided herein. An exemplary method may include: receiving a temperature of a power MOSFET, the temperature being sensed by a temperature sensor; determining a resistance of the power MOSFET using the received temperature; receiving a voltage across the power MOSFET, the voltage being measured by a differential amplifier; calculating a current provided to an electrical load by the power MOSFET using the determined resistance of the power MOSFET and the received voltage; comparing the calculated current to a predetermined threshold; and switching the power MOSFET to an off state in response to the calculated current exceeding the predetermined threshold.

FIELD OF THE INVENTION

The present technology pertains to monitoring, and more specifically tocurrent monitoring.

BACKGROUND ART

Electricity is essential to electronic devices, such asportable/wearable computer and communications systems, home appliances,entertainment systems, office equipment, industrial robots, serverfarms/data centers, telecommunications equipment, military systems,marine electronics, and the like. Monitoring the amount of currentdelivered to a system/load is critical for understanding, for example,the system's impact on battery life, safety decisions in over-currentprotection circuits, the system's health, and establishing system andsubsystem power budgets/allowances.

SUMMARY OF THE INVENTION

In some embodiments, the present technology is directed to a system forcurrent monitoring which may include an electrical load; a power MOSFETelectrically coupled to the electrical load; a differential amplifierelectrically coupled to the power MOSFET; a temperature sensor thermallycoupled to the power MOSFET; a processor communicatively coupled to thedifferential amplifier and the temperature sensor; and a memorycommunicatively coupled to the processor. The memory mays storeinstructions executable by the processor to perform a method comprising:receiving a temperature of the power MOSFET, the temperature beingsensed by the temperature sensor, determining a resistance of the powerMOSFET using the received temperature, receiving a voltage across thepower MOSFET, the voltage being measured by the differential amplifier,calculating a current provided to the electrical load by the powerMOSFET using the determined resistance of the power MOSFET and thereceived voltage, comparing the calculated current to a predeterminedthreshold, and switching the power MOSFET to an off state in response tothe calculated current exceeding the predetermined threshold.

In some embodiments, the present technology is directed to a method formonitoring current performed by a processor. The method may includereceiving a temperature of a power MOSFET, the temperature being sensedby a temperature sensor; determining a resistance of the power MOSFETusing the received temperature; receiving a voltage across the powerMOSFET, the voltage being measured by a differential amplifier;calculating a current provided to an electrical load by the power MOSFETusing the determined resistance of the power MOSFET and the receivedvoltage; comparing the calculated current to a predetermined threshold;and switching the power MOSFET to an off state in response to thecalculated current exceeding the predetermined threshold.

In some embodiments, the present technology is directed to anon-transitory computer-readable storage medium having embodied thereoninstructions, the instructions being executable by a processor toperform a method for current monitoring. The method may includereceiving a temperature of a power MOSFET, the temperature being sensedby a temperature sensor; determining a resistance of the power MOSFETusing the received temperature; receiving a voltage across the powerMOSFET, the voltage being measured by a differential amplifier;calculating a current provided to an electrical load by the power MOSFETusing the determined resistance of the power MOSFET and the receivedvoltage; comparing the calculated current to a predetermined threshold;and switching the power MOSFET to an off state in response to thecalculated current exceeding the predetermined threshold.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, where like reference numerals refer toidentical or functionally similar elements throughout the separateviews, together with the detailed description below, are incorporated inand form part of the specification, and serve to further illustrateembodiments of concepts that include the claimed disclosure, and explainvarious principles and advantages of those embodiments. The methods andsystems disclosed herein have been represented where appropriate byconventional symbols in the drawings, showing only those specificdetails that are pertinent to understanding the embodiments of thepresent disclosure so as not to obscure the disclosure with details thatwill be readily apparent to those of ordinary skill in the art havingthe benefit of the description herein.

FIG. 1A is a simplified diagram of a system, according to someembodiments.

FIG. 1B is a simplified diagram of a system, according to variousembodiments.

FIG. 2 is a simplified diagram illustrating current monitoring in asystem, according to some embodiments.

FIG. 3A is a simplified diagram illustrating current monitoring in asystem, according to various embodiments.

FIG. 3B is a chart illustrating an effect of temperature on a switchcharacteristic, according to some embodiments.

FIG. 3C is a chart illustrating an effect of temperature on currentmonitoring accuracy, according to some embodiments.

FIG. 3D is a simplified schematic of circuits, according to someembodiments.

FIG. 4 is a simplified diagram illustrating temperature-compensatedcurrent monitoring in a system, according to some embodiments.

FIG. 5 is a simplified diagram illustrating temperature-compensatedcurrent monitoring in a system, according to various embodiments.

FIG. 6 is a simplified diagram illustrating various aspects of a systemfor temperature-compensated current monitoring, according to someembodiments.

FIG. 7 is a flow diagram of a method for temperature-compensated currentmonitoring, according to some embodiments.

FIG. 8 is a simplified block diagram of a computing system, according tosome embodiments.

DETAILED DESCRIPTION

While this technology is susceptible of embodiment in many differentforms, there is shown in the drawings and will herein be described indetail several specific embodiments with the understanding that thepresent disclosure is to be considered as an exemplification of theprinciples of the technology and is not intended to limit the technologyto the embodiments illustrated. The terminology used herein is for thepurpose of describing particular embodiments only and is not intended tobe limiting of the technology. As used herein, the singular forms “a,”“an,” and “the” are intended to include the plural forms as well, unlessthe context clearly indicates otherwise. It will be further understoodthat the terms “includes,” “including,” “comprises,” and/or“comprising,” when used in this specification, specify the presence ofstated features, integers, steps, operations, elements, and/orcomponents, but do not preclude the presence or addition of one or moreother features, integers, steps, operations, elements, components,and/or groups thereof. It will be understood that like or analogouselements and/or components, referred to herein, may be identifiedthroughout the drawings with like reference characters. It will befurther understood that several of the figures are merely schematicrepresentations of the present technology. As such, some of thecomponents may have been distorted from their actual scale for pictorialclarity.

FIG. 1A shows system 100 including power apparatus 130 and load 120.Power apparatus 130 is electrically coupled to load 120. In someembodiments, power apparatus 130 is, for example, a power supply and/ora power distribution unit. A power supply is an electronic device thatsupplies electric energy to an electrical load, such as load 120. Powersupplies convert one form of electrical energy to another; powersupplies may also be referred to as electric power converters. A powerdistribution unit is an apparatus for distributing and controllingelectrical power (e.g., to one or more of load 120) and can includemultiple electrical outlets.

Power apparatus 130 may include power filtering, intelligent loadbalancing, and/or remote monitoring and control (e.g., turningindividual loads on and/or off) functions. Power apparatus 130 mayfurther include a main breaker, individual circuit breakers, and powermonitoring panel (not illustrated in FIG. 1A). Power apparatus 130 canbe in an enclosure (not depicted in FIG. 1A). The enclosure of powerapparatus 130 may made of metal and include openings for a powermonitoring panel, power input receptacle, and/or power outlets. A powermonitoring panel may provide output to a user (e.g., status information,notifications, warnings, etc.) and receive input from the user. Forexample, the power monitoring panel includes at least some of thefeatures of a computing system described in relation to FIG. 8. Anenclosure of power apparatus 130 may include shielding to at leastpartially block electromagnetic interference (EMI; also calledradio-frequency interference (RFI) when in radio frequency).

Power apparatus 130 includes switch 110. Switch 110 can turn on and/oroff electrical power provided by power apparatus 130 to load 120. Switch110 includes three terminals: control input 116, power input 114, andpower output 118. Control input 116 controls the operation/state ofswitch 110 (e.g., “on” and/or “off”). Electrical power is received byswitch 110 at power input 114. For example, electrical power received atpower input 114 is in the range of 24-32 Volts and 50-150 Amps. Switch110 may turn on and/or off electrical power provided to load 120 throughpower output 118. For example, electrical power provided at power output118 is in the range of 24-32 Volts and 50-150 Amps.

Load 120 is an electrical device which receives electrical power frompower apparatus 130. For example, load 120 can be one or more ofportable/wearable computer and communications system, home appliance,home entertainment system, office equipment, industrial robot, server(server farm/data center), telecommunications equipment, militarysystems, marine electronics, avionics, and the like.

As shown in FIG. 1B, switch 110 (FIG. 1A) may be a power metal-oxidesemiconductor field-effect transistor (MOSFET) 110 a. Power MOSFET 110 aincludes three terminals: drain 114 a, gate 116 a, and source 118 a,which may correspond to power input 114, control input 116, and poweroutput 118 of switch 110, respectively. A power MOSFET is a type ofMOSFET designed to handle significant power levels. For example, powerMOSFET 110 a receives and/or provides electricity in the range of 24-32Volts and 50-150 Amps. In some embodiments, power provided at source 118a is approximately the same as the power received at drain 114 a (e.g.,voltage provided at source 118 a is based on a voltage received at gate116 a and a drop voltage of a body diode intrinsic to power MOSFET 110a). Power MOSFET 110 a is, by way of non-limiting example, an InfineonIPT007N06N. Although MOSFET 110 a as depicted in FIG. 1B is an n-channel(nmos or n-type) power MOSFET, various embodiments may use a p-channel(pmos or p-type) power MOSFET.

Drain 114 a is electrically coupled to a power or voltage source (notshown in FIG. 1B). Source 118 a is electrically coupled to electric load120. Load 120 is electrically coupled to ground 140. In this way, powerMOSFET 110 a is in a high-side configuration, source 118 a not having adirect connection to ground 140. A low-side configuration, whereelectric load 120 is coupled to drain 114 a and source 118 a is coupledto the ground, may also be used.

Various aspects of power apparatus 130, including power MOSFET 110 a,according to various embodiments are described further in relation toFIG. 6.

FIG. 2 depicts system 200 for current monitoring using shunt resistor210, according to some embodiments. Shunt resistor 210 is disposedbetween switch 110 and load 120. Since shunt resistor 210 is in serieswith load 120, a voltage V_(SHUNT) is generated across shunt resistor210 that is proportional to a current provided to load 120 I_(LOAD). Inother words, using Ohm's Law, I_(LOAD) can be determined using theresistance of shunt resistor 210 and V_(SHUNT). Ohm's law states thatthe current through a conductor between two points is directlyproportional to the potential difference across the two points, where aresistance of the conductor is the proportionality term. V_(SHUNT) canbe measured by differential amplifier 220. Differential amplifier 220,by way of non-limiting example, is one or more of a current shuntmonitor (CSM), operational amplifier (op-amp), difference amplifier(DA), instrumentation amplifier (IA), and the like.

Current monitoring using shunt resistor 210 suffers from thedisadvantage of reduced efficiency arising from power loss incurredthrough shunt resistor 210. For example, a 0.001 Ohms resistance (ofshunt resistor 210) will consume 2.5 Watts (producing heat) at 50 Amps.In addition, the additional heat (produced by shunt resistor 210) canshorten the life of electrical devices, including power apparatus 130,so higher costs associated with further thermal management may beincurred.

FIG. 3A illustrates system 300 for current monitoring using acharacteristic series resistance of switch 110 (e.g., power MOSFET 110a) R_(DS), according to some embodiments. When MOSFET 110 a isconducting (e.g., power is provided to load 120 by power apparatus 130),MOSFET 110 a is in a triode region of operation and acts as a linearresistor having resistance R_(DS). For example, R_(DS) is the resistancebetween drain 114 a and source 118 a of MOSFET 110 a. For example,V_(DS) is the voltage across MOSFET 110 a (e.g., voltage across drain114 a and source 118 a of MOSFET 110 a). V_(DS) can be measured bydifferential amplifier 320. Differential amplifier 320, by way ofnon-limiting example, is one or more of a current shunt monitor (CSM),operational amplifier (op-amp), difference amplifier (DA),instrumentation amplifier (IA), and the like. Using Ohm's Law, I_(LOAD)can be determined using V_(DS) and R_(DS).

The R_(DS) of MOSFET 110 a is a strong function of temperature. FIG. 3Bshows an example graph 350 of R_(DS) over temperature. As shown in FIG.3B, R_(DS) is from 0.00108 Ohms-0.00126 Ohms over temperatures from −40°C. to +140° C. At lower temperatures R_(DS) is a smaller value and athigher temperatures R_(DS) is a larger value.

Since R_(DS) changes with temperature, the accuracy of currentmonitoring—using R_(DS) values based on temperature assumptions—isseverely reduced. FIG. 3C shows an example graph 370 of currentcalculated at temperature from −40° C. to +140° C. For example, thecurrent calculated assuming a 40° C. temperature has only a ±8% accuracyover the −40° C. to +140° C. temperature range.

FIG. 3D shows a non-limiting example of (simulation) circuits 390 whichmay be used to determine R_(DS) and I_(LOAD) (e.g., as shown in FIGS. 3Band 3C), according to some embodiments.

FIG. 4 shows system 400 for temperature-compensated current monitoring,including power apparatus 130 and load 120. Power apparatus 130 includespower MOSFET 110 a, temperature sensor 410, differential amplifier 420,and processor 430. Temperature sensor 410 is thermally coupled to powerMOSFET 110 a. Temperature sensor 410 and power MOSFET 110 a aredescribed further in relation to FIG. 6. Differential amplifier 420 iselectrically coupled to power MOSFET 110 a. Processor 430 iscommunicatively coupled to temperature sensor 410 and differentialamplifier 420.

Temperature sensor 410 determines a temperature of power MOSFET 110 a.Temperature sensor 410, by way of non-limiting example, is one or moreof a thermocouple, resistive temperature device (RTD), thermistor, andintegrated silicon-based sensor. Integrated silicon-based sensors mayintegrate a temperature sensor and signal-conditioning circuitry in asingle chip/device. Other temperature sensing technologies may be used,for example, infrared (e.g., pyrometer) and thermal pile. In someembodiments, temperature sensor 410 is an analog temperature sensor thatconverts temperature to an analog voltage, such as a MicrochipTechnology Inc. MCP9700A.

Differential amplifier 420 determines V_(DS). For example, differentialamplifier 420 is electrically coupled to drain 114 a and source 118 a ofMOSFET 110 a. Differential amplifier 420, by way of non-limitingexample, is one or more of a current shunt monitor (CSM), operationalamplifier (op-amp), difference amplifier (DA), instrumentation amplifier(IA), and the like. In some embodiments, differential amplifier 420 isan LM344 op-amp (e.g., operating in differential mode). By way ofnon-limiting example, differential amplifier 420 is at least one of aTexas Instruments LMV341, LMV342, and LMV344.

Processor 430 determines I_(LOAD) using signals from temperature sensor410 and differential amplifier 420. For example, signals fromtemperature sensor 410 and/or differential amplifier 420 are digitalsignals representing values for temperature and/or voltage,respectively. Alternatively or additionally, signals from temperaturesensor 410 and/or differential amplifier 420 are analog signalsincluding values for temperature and/or voltage, respectively.

Processor 430 may integrate one or more analog-to-digital converters(ADCs; not shown in FIG. 4). ADCs convert a continuous physical quantity(e.g., voltage) to a digital number that represents the quantity'samplitude. Alternatively or additionally, one or more ADCs may beexternal to processor 430 and be disposed in at least one signal pathbetween processor 430 and at least one of temperature sensor 410 anddifferential amplifier 420.

In some embodiments, processor 430 is an embedded processor disposed onor in power apparatus 130. For example, processor 430 is an ARMprocessor, such as a Freescale Kinetis microcontroller (e.g., KL95Z32,KL25Z32, etc.). ARM is a family of instruction set architectures forcomputer processors based on a reduced instruction set computing (RISC)architecture developed by British company ARM Holdings. By way offurther non-limiting example, processor 430 is an embedded processorhaving at least one of: on-chip RAM, on-chip non-volatile memory,on-chip ADC, on-chip digital-to-analog converter (DAC), and the like. Invarious embodiments, processor 430 is at least one of: a mobile,desktop, and cloud-based computing system communicatively coupled topower apparatus 130. For example, processor 430 is communicativelycoupled to power apparatus 130 through wired and/or wireless networks.Processor 430 and networks are described further in relation to FIG. 8.

The R_(DS) of MOSFET 110 a may be determined (e.g., by processor 430)using a temperature measured by temperature sensor 410. For example, amathematical relationship between a measured temperature and R_(DS) isrepresented by an empirically derived (e.g., from simulations and/orbench measurements such as reflected in FIGS. 3B and 3C) second-orderpolynomial.

By way of non-limiting example, the second-order polynomial is:R _(DS)=6.46229×10⁻⁹(Temp)²+2.44568×10⁻⁶(Temp)+0.000588037  (1)where Temp is the temperature. For example, Equation 1 may be derivedusing a (simulation) circuit shown in FIG. 3D to apply a constant loadof 10 Amps (other loads may be used) over a discrete range temperaturesfrom 20° C.-100° C. (other temperature ranges may be used) to determinecorresponding V_(DS) values. R_(DS) values are calculated using thedetermined V_(DS) values:R _(DS) =V _(DS)/10 Amps  (2)The calculated R_(DS) values and associated temperature values may berepresented by a data plot (of R_(DS) and temperature). A best-fitsecond-order polynomial for the data plot is determined (e.g., usingMathcad from Parametric Technology Corporation, Excel from MicrosoftCorporation, etc.). Multiple measurements at various known temperaturescan be taken to empirically determine one or more R_(DS)-temperaturecurves from which one or more best-fit lines may be computed. OnceEquation 1 is determined using empirical data, Equation 1 can be used tocalculate R_(DS) as a function of temperature (e.g., using temperaturesensor 410).

Once R_(DS) is computed using a temperature (e.g., temperature measuredby temperature sensor 410) and the best-fit second-order polynomial(e.g., Equation 1), I_(LOAD) (e.g., current provided to load 120 bypower apparatus 130) is calculated:I _(LOAD) =V _(DS) /R _(DS)  (3)

FIG. 5 illustrates system 500 for temperature-compensated currentmonitoring according to various embodiments. As shown in FIG. 5,differential amplifier U6 is a single-ended non-inverting amplifierreferenced to the floating source voltage of MOSFETs M1 (and M2). WhenMOSFETs M1 (and M2) are in the off state, the voltage difference on theinputs of op-amp U6 can be as high as an input voltage (e.g., voltageseen at drain 114 a), V_(IN) (e.g., 28 Volts). Since op-amp inputsgenerally cannot withstand a voltage substantially above its powersupply input (e.g., V_(cc)), zener diode D3 provides protection. Currentlimiting resistor R11 can be any value suitable for cancelling op-ampcurrent offset.

By way of non-limiting example, op-amp U6 has a fixed gain of 5× toimprove ADC resolution and allow for an increase in R_(DS) that will (atmaximum) double the measured voltage. Other gains may be used. In someembodiments, input voltage offset is not trimmed out in hardware buttrimmed out in a calibration process as a software offset removal.

Single-ended non-inverting op-amp U6 offers advantages over adifferential op-amp when, for example, microcontroller 430 has built inDAC and ADC functions to both read the current and provide a referencevoltage for a high-speed comparator (e.g., for handling instant tripprotection). In some embodiments where microcontroller 430 does notinclude DAC and ADC functions, a differential op-amp (e.g., FIG. 4) maybe used.

FIG. 6 depicts module 600 of power apparatus 130 (FIGS. 1-4). Module 600includes two power MOSFETs 110 a ₁ and 110 a ₂, temperature sensor 410disposed between MOSFETs 110 a ₁ and 110 a ₂, and substrate 610. Module600 includes connectors 630 for physical and electrical connection withother components of power apparatus 130 (not shown in FIG. 6).

In some embodiments, Substrate 610 is a printed circuit board (PCB)comprising one or more metal and dielectric layers. For example, themetal layer is copper and the dielectric layer is at least one of:polytetrafluoroethylene (e.g., Teflon), FR-2 (e.g., phenolic cottonpaper), FR-3 (e.g., cotton paper and epoxy), FR-4 (e.g., woven glass andepoxy), FR-5 (e.g., woven glass and epoxy), FR-6 (e.g., matte glass andpolyester), G-10 (e.g., woven glass and epoxy), CEM-1 (e.g., cottonpaper and epoxy), CEM-2 (e.g., cotton paper and epoxy), CEM-3 (e.g.,non-woven glass and epoxy), CEM-4 (e.g., woven glass and epoxy), CEM-5(e.g., woven glass and polyester), and the like. Connectors 630 may becomprised of at least one of: one or more metal and dielectric layers ofsubstrate 610, metal leads, and an electrical connector.

In some embodiments, heat sink 620 may be mechanically and/or thermallycoupled to power MOSFETs 110 a ₁ and 110 a ₂. For example, heat sink 620is disposed over a top surface of power MOSFETs 110 a ₁ and 110 a ₂. Theheat sink may be mechanically and thermally coupled to power MOSFETs 110a ₁ and 110 a ₂ using one or more of clips, pins, springs, standoffs,thermal tape, epoxy, thermal grease, and the like. Heat sinks arepassive heat exchangers that cool power MOSFETs 110 a ₁ and 110 a ₂ bydissipating heat into the surrounding medium. By way of non-limitingexample, heat sink 620 is comprised of at least one of: copper andaluminum alloy. In some embodiments, temperature sensor 410 is thermallycoupled to heat sink 620. By way of further non-limiting example,temperature sensor 410 is disposed on or under heat sink 620 andin-between power MOSFETs 110 a ₁ and 110 a ₂.

Other combinations and permutations may be used in accordance withvarious embodiments. For example, any number of power MOSFET 110 a isincluded in module 600 (e.g., a single power MOSFET or an array of powerMOSFETS); any number of temperature sensor 410 is included in module600; each of temperature sensor 410 measures temperature for one powerMOSFET 110 a or more than one power MOSFET 110 a; any number of heatsink 620 is included in module 600; each heat sink 620 is thermallycoupled to one power MOSFET or more than one power MOSFET 110 a; andtemperature sensor 410 is disposed on, in, under, or proximate to atleast one heat sink 620 and/or proximate to at least one power MOSFET(s)110 a.

FIG. 7 illustrates a method 700 for temperature-compensated currentmonitoring according to some embodiments. In various embodiments, atleast some of steps 710-770 are performed by processor 430 (FIG. 4).

At Step 710, a pre-determined current limit I_(LIMIT) is received. Forexample, I_(LIMIT) is an upper threshold at and/or above which load 120(FIGS. 1-4) has a condition (marginal condition/poor health, impendingfailure, and the like). Other current limits may be used, for example,I_(LIMIT) is a lower threshold at and/or below which load 120 hascondition, or I_(LIMIT1) is an upper threshold at and/or above whichload 120 has a first condition and I_(LIMIT2) is a lower threshold atand/or below which load 120 has a second condition.

At Step 720, a temperature is received. For example, a temperature is anoutput from temperature sensor 410 (FIGS. 4 and 5) processed by an ADC.In some embodiments, the received temperature is the temperature of oneor more power MOSFETs 110 a.

At Step 730, resistance R_(DS) is computed. In some embodiments, R_(DS)is computed using the received temperature and a second order polynomialequation (e.g., Equation 1).

At Step 740, voltage V_(DS) is received. For example, V_(DS) is anoutput from differential amplifier 420 (FIG. 4) and/or op-amp U6 (FIG.5) processed by an ADC.

At Step 750, current I_(LOAD) is calculated. In some embodiments,I_(LOAD) is calculated using the computed R_(DS), the received V_(DS),and Ohm's Law (e.g., Equation 3).

At Step 760, I_(LOAD) is compared to I_(LIMIT). In some embodiments,whether I_(LOAD) is equal to and/or greater than I_(LIMIT) isdetermined. Other comparisons may be used, for example, whether I_(LOAD)is equal to and/or greater than I_(LIMIT), or whether I_(LOAD) is equalto and/or greater than I_(LIMIT1) and whether I_(LOAD) is equal toand/or less than I_(LIMIT2). When the comparison condition(s) is notsatisfied, method 700 may continue to Step 710 or 720. When thecomparison condition(s) is satisfied, method 700 may continue to Step770.

At Step 770, power MOSFET 110 a is switched to an off state (and currentremoved from load 120) and/or a notification is provided to a user. Forexample, source 116 a is used to turn switch 110 a to an off state, atleast cutting electrical power to load 120. In some embodiments, theprovided notification directs a user to service (e.g., performpreventative maintenance on) load 120. By way of non-limiting example,servicing includes at least one of: inspecting load 120, performingdiagnostic tests on load 120, and replacing load 120 with a serviceableunit, averting unscheduled and/or catastrophic interruptions in theoperation of system 100, 200, 300, and/or 400 (FIGS. 1-4). In someembodiments, the notification is provided through at least one of alight-emitting diode (LED) on or about power apparatus 130, a powermonitoring panel of power apparatus 130 (FIGS. 1-4), in an email, in anSMS message, in a pre-recorded audio message played during an automatedtelephone call to the user, in an audible alarm of power apparatus 130,and the like.

Various embodiments of the present invention offer one or more of theadvantages of higher accuracy for current monitoring, reduced wastedelectrical power, and decreased generated heat. In some embodiments, thecalculated I_(LOAD)—when there is a 10° C. difference between thetemperature from temperature sensor 410 (FIG. 4) and a junctiontemperature of power MOSFET 110 a (FIGS. 3 and 4)—is still within 0.8%of an actual I_(LOAD).

FIG. 8 illustrates an exemplary computer system 800 that may be used toimplement some embodiments of the present invention. The computer system800 in FIG. 8 may be implemented in the contexts of the likes ofcomputing systems, networks, servers, or combinations thereof. Thecomputer system 800 in FIG. 8 includes one or more processor units 810and main memory 820. Main memory 820 stores, in part, instructions anddata for execution by processor units 810. Main memory 820 stores theexecutable code when in operation, in this example. The computer system800 in FIG. 8 further includes a mass data storage 830, portable storagedevice 840, output devices 850, user input devices 860, a graphicsdisplay system 870, and peripheral devices 880.

The components shown in FIG. 8 are depicted as being connected via asingle bus 890. The components may be connected through one or more datatransport means. Processor unit 810 and main memory 820 is connected viaa local microprocessor bus, and the mass data storage 830, peripheraldevice(s) 880, portable storage device 840, and graphics display system870 are connected via one or more input/output (I/O) buses.

Mass data storage 830, which can be implemented with a magnetic diskdrive, solid state drive, or an optical disk drive, is a non-volatilestorage device for storing data and instructions for use by processorunit 810. Mass data storage 830 stores the system software forimplementing embodiments of the present disclosure for purposes ofloading that software into main memory 820.

Portable storage device 840 operates in conjunction with a portablenon-volatile storage medium, such as a flash drive, floppy disk, compactdisk, digital video disc, or Universal Serial Bus (USB) storage device,to input and output data and code to and from the computer system 800 inFIG. 8. The system software for implementing embodiments of the presentdisclosure is stored on such a portable medium and input to the computersystem 800 via the portable storage device 840.

User input devices 860 can provide a portion of a user interface. Userinput devices 860 may include one or more microphones, an alphanumerickeypad, such as a keyboard, for inputting alphanumeric and otherinformation, or a pointing device, such as a mouse, a trackball, stylus,or cursor direction keys. User input devices 860 can also include atouchscreen. Additionally, the computer system 800 as shown in FIG. 8includes output devices 850. Suitable output devices 850 includespeakers, printers, network interfaces, and monitors.

Graphics display system 870 include a liquid crystal display (LCD) orother suitable display device. Graphics display system 870 isconfigurable to receive textual and graphical information and processesthe information for output to the display device.

Peripheral devices 880 may include any type of computer support deviceto add additional functionality to the computer system.

The components provided in the computer system 800 in FIG. 8 are thosetypically found in computer systems that may be suitable for use withembodiments of the present disclosure and are intended to represent abroad category of such computer components that are well known in theart. Thus, the computer system 800 in FIG. 8 can be a personal computer(PC), hand held computer system, telephone, mobile computer system,workstation, tablet, phablet, mobile phone, server, minicomputer,mainframe computer, wearable, or any other computer system. The computermay also include different bus configurations, networked platforms,multi-processor platforms, and the like. Various operating systems maybe used including UNIX, LINUX, WINDOWS, MAC OS, PALM OS, QNX ANDROID,IOS, CHROME, and other suitable operating systems.

Some of the above-described functions may be composed of instructionsthat are stored on storage media (e.g., computer-readable medium). Theinstructions may be retrieved and executed by the processor. Someexamples of storage media are memory devices, tapes, disks, and thelike. The instructions are operational when executed by the processor todirect the processor to operate in accord with the technology. Thoseskilled in the art are familiar with instructions, processor(s), andstorage media.

In some embodiments, the computing system 800 may be implemented as acloud-based computing environment, such as a virtual machine operatingwithin a computing cloud. In other embodiments, the computing system 800may itself include a cloud-based computing environment, where thefunctionalities of the computing system 800 are executed in adistributed fashion. Thus, the computing system 800, when configured asa computing cloud, may include pluralities of computing devices invarious forms, as will be described in greater detail below.

In general, a cloud-based computing environment is a resource thattypically combines the computational power of a large grouping ofprocessors (such as within web servers) and/or that combines the storagecapacity of a large grouping of computer memories or storage devices.Systems that provide cloud-based resources may be utilized exclusivelyby their owners or such systems may be accessible to outside users whodeploy applications within the computing infrastructure to obtain thebenefit of large computational or storage resources.

The cloud is formed, for example, by a network of web servers thatcomprise a plurality of computing devices, such as the computing system800, with each server (or at least a plurality thereof) providingprocessor and/or storage resources. These servers manage workloadsprovided by multiple users (e.g., cloud resource customers or otherusers). Typically, each user places workload demands upon the cloud thatvary in real-time, sometimes dramatically. The nature and extent ofthese variations typically depends on the type of business associatedwith the user.

It is noteworthy that any hardware platform suitable for performing theprocessing described herein is suitable for use with the technology. Theterms “computer-readable storage medium” and “computer-readable storagemedia” as used herein refer to any medium or media that participate inproviding instructions to a CPU for execution. Such media can take manyforms, including, but not limited to, non-volatile media, volatile mediaand transmission media. Non-volatile media include, for example,optical, magnetic, and solid-state disks, such as a fixed disk. Volatilemedia include dynamic memory, such as system RAM. Transmission mediainclude coaxial cables, copper wire and fiber optics, among others,including the wires that comprise one embodiment of a bus. Transmissionmedia can also take the form of acoustic or light waves, such as thosegenerated during radio frequency (RF) and infrared (IR) datacommunications. Common forms of computer-readable media include, forexample, a floppy disk, a flexible disk, a hard disk, magnetic tape, anyother magnetic medium, a CD-ROM disk, digital video disk (DVD), anyother optical medium, any other physical medium with patterns of marksor holes, a RAM, a PROM, an EPROM, an EEPROM, a FLASH memory, any othermemory chip or data exchange adapter, a carrier wave, or any othermedium from which a computer can read.

Various forms of computer-readable media may be involved in carrying oneor more sequences of one or more instructions to a CPU for execution. Abus carries the data to system RAM, from which a CPU retrieves andexecutes the instructions. The instructions received by system RAM canoptionally be stored on a fixed disk either before or after execution bya CPU.

Computer program code for carrying out operations for aspects of thepresent technology may be written in any combination of one or moreprogramming languages, including an object oriented programming languagesuch as JAVA, SMALLTALK, C++ or the like and conventional proceduralprogramming languages, such as the “C” programming language or similarprogramming languages. The program code may execute entirely on theuser's computer, partly on the user's computer, as a stand-alonesoftware package, partly on the user's computer and partly on a remotecomputer or entirely on the remote computer or server. In the latterscenario, the remote computer may be connected to the user's computerthrough any type of network, including a local area network (LAN) or awide area network (WAN), or the connection may be made to an externalcomputer (for example, through the Internet using an Internet ServiceProvider).

The corresponding structures, materials, acts, and equivalents of allmeans or step plus function elements in the claims below are intended toinclude any structure, material, or act for performing the function incombination with other claimed elements as specifically claimed. Thedescription of the present technology has been presented for purposes ofillustration and description, but is not intended to be exhaustive orlimited to the invention in the form disclosed. Many modifications andvariations will be apparent to those of ordinary skill in the artwithout departing from the scope and spirit of the invention. Exemplaryembodiments were chosen and described in order to best explain theprinciples of the present technology and its practical application, andto enable others of ordinary skill in the art to understand theinvention for various embodiments with various modifications as aresuited to the particular use contemplated.

Aspects of the present technology are described above with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems) and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer program instructions. These computer program instructions maybe provided to a processor of a general purpose computer, specialpurpose computer, or other programmable data processing apparatus toproduce a machine, such that the instructions, which execute via theprocessor of the computer or other programmable data processingapparatus, create means for implementing the functions/acts specified inthe flowchart and/or block diagram block or blocks.

These computer program instructions may also be stored in a computerreadable medium that can direct a computer, other programmable dataprocessing apparatus, or other devices to function in a particularmanner, such that the instructions stored in the computer readablemedium produce an article of manufacture including instructions whichimplement the function/act specified in the flowchart and/or blockdiagram block or blocks.

The computer program instructions may also be loaded onto a computer,other programmable data processing apparatus, or other devices to causea series of operational steps to be performed on the computer, otherprogrammable apparatus or other devices to produce a computerimplemented process such that the instructions which execute on thecomputer or other programmable apparatus provide processes forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks.

The flowchart and block diagrams in the Figures illustrate thearchitecture, functionality, and operation of possible implementationsof systems, methods, and computer program products according to variousembodiments of the present technology. In this regard, each block in theflowchart or block diagrams may represent a module, segment, or portionof code, which comprises one or more executable instructions forimplementing the specified logical function(s). It should also be notedthat, in some alternative implementations, the functions noted in theblock may occur out of the order noted in the figures. For example, twoblocks shown in succession may, in fact, be executed substantiallyconcurrently, or the blocks may sometimes be executed in the reverseorder, depending upon the functionality involved. It will also be notedthat each block of the block diagrams and/or flowchart illustration, andcombinations of blocks in the block diagrams and/or flowchartillustration, can be implemented by special purpose hardware-basedsystems that perform the specified functions or acts, or combinations ofspecial purpose hardware and computer instructions.

While the present technology has been described in connection with aseries of preferred embodiment, these descriptions are not intended tolimit the scope of the technology to the particular forms set forthherein. It will be further understood that the methods of the technologyare not necessarily limited to the discrete steps or the order of thesteps described. To the contrary, the present descriptions are intendedto cover such alternatives, modifications, and equivalents as may beincluded within the spirit and scope of the technology as defined by theappended claims and otherwise appreciated by one of ordinary skill inthe art.

What is claimed is:
 1. A system for monitoring current comprising: anelectrical load; a power MOSFET electrically coupled to the electricalload; a differential amplifier electrically coupled to the power MOSFET;a temperature sensor thermally coupled to the power MOSFET; a processorcommunicatively coupled to the differential amplifier and thetemperature sensor; and a memory communicatively coupled to theprocessor, the memory storing instructions executable by the processorto perform a method comprising: receiving a temperature of the powerMOSFET, the temperature being sensed by the temperature sensor, thereceiving the temperature of the power MOSFET including: receiving ananalog voltage from the temperature sensor, the analog voltagerepresenting the temperature of the power MOSFET, and converting theanalog voltage to a digital number by an analog to digital converter,the digital number representing the temperature of the power MOSFET,determining a resistance of the power MOSFET using the digital numberrepresenting the temperature, receiving a voltage across the powerMOSFET, the voltage being measured by the differential amplifier,calculating a current provided to the electrical load by the powerMOSFET using the determined resistance of the power MOSFET and thereceived voltage, comparing the calculated current to a predeterminedthreshold, and switching the power MOSFET to an off state in response tothe calculated current exceeding the predetermined threshold.
 2. Thesystem of claim 1 further comprising: a display, the display providing anotification to a user.
 3. The system of claim 1 further comprising: asubstrate, the power MOSFET and the temperature sensor being disposed onthe substrate.
 4. The system of claim 1 further comprising: a heat sink,the heatsink being thermally coupled to the power MOSFET and thetemperature sensor.
 5. The system of claim 1 wherein the method furthercomprises: providing a notification to a user in response to thecalculated current exceeding the predetermined threshold, thenotification directing the user to service the electrical load.
 6. Thesystem of claim 1 wherein the power MOSFET is an n-type MOSFET.
 7. Thesystem of claim 6 wherein the power MOSFET is in a high-sideconfiguration.
 8. The system of claim 1 wherein the power MOSFET is ap-type MOSFET.
 9. The system of claim 1 wherein the differentialamplifier is a single-ended non-inverting op-amp operating.
 10. Thesystem of claim 1 wherein the differential amplifier is at least one ofa current shunt monitor (CSM), difference amplifier (DA), andinstrumentation amplifier (IA).
 11. The system of claim 1 wherein thetemperature sensor is an integrated silicon-based sensor.
 12. The systemof claim 1 wherein the temperature sensor is at least one of athermocouple, resistive temperature device (RTD), and thermistor.
 13. Amethod for current monitoring by a processor comprising: receiving atemperature of a power MOSFET, the temperature being sensed by atemperature sensor, the receiving the temperature of the power MOSFETincluding: receiving an analog voltage from the temperature sensor, theanalog voltage representing the temperature of the power MOSFET, andconverting the analog voltage to a digital number by an analog todigital converter, the digital number representing the temperature ofthe power MOSFET; determining a resistance of the power MOSFET using thedigital number representing the temperature; receiving a voltage acrossthe power MOSFET, the voltage being measured by a differentialamplifier; calculating a current provided to an electrical load by thepower MOSFET using the determined resistance of the power MOSFET and thereceived voltage; comparing the calculated current to a predeterminedthreshold; and switching the power MOSFET to an off state in response tothe calculated current exceeding the predetermined threshold.
 14. Themethod of claim 13 wherein determining the resistance of the powerMOSFET includes using the digital number representing the temperature toevaluate a second order polynomial.
 15. The method of claim 13 whereincalculating the current includes using the determined resistance of thepower MOSFET and the received voltage to evaluate Ohm's Law.
 16. Themethod of claim 13 further comprising: providing a notification to auser in response to the calculated current exceeding the predeterminedthreshold, the notification directing the user to service the electricalload.
 17. A system for monitoring current comprising: an electricalload; a power MOSFET electrically coupled to the electrical load; adifferential amplifier electrically coupled to the power MOSFET; atemperature sensor thermally coupled to the power MOSFET; a processorcommunicatively coupled to the differential amplifier and thetemperature sensor; and a memory communicatively coupled to theprocessor, the memory storing instructions executable by the processorto perform a method comprising: receiving a temperature of the powerMOSFET, the temperature being sensed by the temperature sensor,determining a resistance of the power MOSFET using the receivedtemperature, receiving a voltage across the power MOSFET, the voltagebeing measured by the differential amplifier, the receiving the voltageacross the power MOSFET including: receiving an analog voltage from thedifferential amplifier, the analog voltage representing the temperatureof the power MOSFET, and converting the analog voltage to a digitalnumber by an analog to digital converter, the digital numberrepresenting the voltage across the power MOSFET, calculating a currentprovided to the electrical load by the power MOSFET using the determinedresistance of the power MOSFET and the digital number representing thevoltage, comparing the calculated current to a predetermined threshold,and switching the power MOSFET to an off state in response to thecalculated current exceeding the predetermined threshold.
 18. The systemof claim 17 further comprising: a display, the display providing anotification to a user.
 19. The system of claim 17 further comprising: asubstrate, the power MOSFET and the temperature sensor being disposed onthe substrate.
 20. The system of claim 17 further comprising: a heatsink, the heat sink being thermally coupled to the power MOSFET and thetemperature sensor.
 21. The system of claim 17 wherein the methodfurther comprises: providing a notification to a user in response to thecalculated current exceeding the predetermined threshold, thenotification directing the user to service the electrical load.
 22. Thesystem of claim 17 wherein the power MOSFET is an n-type MOSFET.
 23. Thesystem of claim 22 wherein the power MOSFET is in a high-sideconfiguration.
 24. The system of claim 17 wherein the power MOSFET is ap-type MOSFET.
 25. The system of claim 17 wherein the differentialamplifier is a single-ended non-inverting op-amp operating.
 26. Thesystem of claim 17 wherein the differential amplifier is at least one ofa current shunt monitor (CSM), difference amplifier (DA), andinstrumentation amplifier (IA).
 27. The system of claim 17 wherein thetemperature sensor is at least one of an integrated silicon-basedsensor, thermocouple, resistive temperature device (RTD), andthermistor.
 28. A method for current monitoring by a processorcomprising: receiving a temperature of a power MOSFET, the temperaturebeing sensed by a temperature sensor; determining a resistance of thepower MOSFET using the received temperature; receiving a voltage acrossthe power MOSFET, the voltage being measured by a differentialamplifier, the receiving the voltage across the power MOSFET including:receiving an analog voltage from the differential amplifier, the analogvoltage representing the temperature of the power MOSFET, and convertingthe analog voltage to a digital number by an analog to digitalconverter, the digital number representing the voltage across the powerMOSFET; calculating a current provided to an electrical load by thepower MOSFET using the determined resistance of the power MOSFET and thedigital number representing the voltage; comparing the calculatedcurrent to a predetermined threshold; and switching the power MOSFET toan off state in response to the calculated current exceeding thepredetermined threshold.
 29. The method of claim 28 wherein determiningthe resistance of the power MOSFET includes using the receivedtemperature to evaluate a second order polynomial.
 30. The method ofclaim 28 wherein calculating the current includes using the determinedresistance of the power MOSFET and the digital number representing thevoltage to evaluate Ohm's Law.